ISO 13166:2020

Water quality — Uranium isotopes — Test method using alpha-spectrometry

This document specifies the conditions for the determination of uranium isotope activity concentration in samples of environmental water (including sea waters) using alpha-spectrometry and 232U as a yield tracer. A chemical separation is required to separate and purify uranium from a test portion of the sample.

Qualité de l'eau — Isotopes de l'uranium — Méthode d'essai par spectrométrie alpha

Le présent document spécifie les conditions relatives à la détermination de l'activité volumique des isotopes de l'uranium dans des échantillons d'eau environnementale (y compris les eaux de mer) par spectrométrie alpha en utilisant 232U comme traceur. Une séparation chimique est requise pour séparer et purifier l'uranium de la prise d'essai.

General Information

• Status: Published
• Publication Date: 03-Aug-2020
• ICS: 13.060.60 - Examination of physical properties of water
• ICS: 13.280 - Radiation protection
• Technical Committee: ISO/TC 147/SC 3 - Radioactivity measurements
• Drafting Committee: ISO/TC 147/SC 3 - Radioactivity measurements
• Current Stage: 6060 - International Standard published
• Start Date: 04-Aug-2020
• Due Date: 22-May-2021
• Completion Date: 04-Aug-2020

Relations

• Revises: ISO 13166:2014 - Water quality — Uranium isotopes — Test method using alpha-spectrometry
• Effective Date: 23-Apr-2020

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 13166
Second edition
2020-08
Water quality — Uranium isotopes —
Test method using alpha-spectrometry
Qualité de l'eau — Isotopes de l'uranium — Méthode d'essai par
spectrométrie alpha
Reference number
ISO 13166:2020(E)
©
ISO 2020

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ISO 13166:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
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Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

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ISO 13166:2020(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
4 Principle . 2
5 Chemical reagents and equipment . 3
5.1 General . 3
5.2 Chemical reagents . 3
5.3 Equipment . 4
6 Sampling and samples . 4
6.1 Sampling . 4
6.2 Sample storage . 4
7 Separation and measurement . 5
7.1 Chemical steps . 5
7.2 Measurement . 5
7.2.1 Quality control . 5
7.2.2 Chemical yield . 5
7.2.3 Background. 5
8 Expression of results . 6
8.1 Spectrum analysis . 6
8.2 Calculation of activity concentration . 6
8.3 Standard uncertainty . 6
8.4 Decision threshold . 7
8.5 Detection limit . 7
8.6 Limits of the coverage interval . 8
8.6.1 Limits of the probabilistically symmetric coverage interval. 8
8.6.2 The shortest coverage interval . 8
9 Test report . 9
Annex A (informative) Chemical separation of uranium .10
Annex B (informative) Precipitation of the source by electrodeposition .13
Annex C (informative) Preparation of the source by coprecipitation .16
Annex D (informative) Occurrence of uranium isotopes .18
Bibliography .19
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ISO 13166:2020(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 3,
Radiological methods.
This second edition cancels and replaces the first edition (ISO 13166:2014), of which it constitutes a
minor revision. The changes compared to the previous edition are as follows:
— update of the common introduction;
— update of the text considering the new ISO 11929 series published in 2019.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
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ISO 13166:2020(E)

Introduction
Radioactivity from several naturally occurring and anthropogenic sources is present throughout
the environment. Thus, water bodies (e.g. surface waters, ground waters, sea waters) can contain
radionuclides of natural, human-made, or both origins:
40 3 14
— Natural radionuclides, including K, H, C, and those originating from the thorium and uranium
226 228 234 238 210
decay series, in particular Ra, Ra, U, U, and Pb, can be found in water for natural reasons
(e.g. desorption from the soil and wash off by rain water) or can be released from technological
processes involving naturally occurring radioactive materials (e.g. the mining and processing of
mineral sands or phosphate fertilizer production and use);
— Human-made radionuclides, such as transuranium elements (americium, plutonium, neptunium,
3 14 90
curium), H, C, Sr, and gamma emitting radionuclides can also be found in natural waters.
Small quantities of these radionuclides are discharged from nuclear fuel cycle facilities into the
environment as the result of authorized routine releases. Some of these radionuclides used for
medical and industrial applications are also released into the environment after use. Anthropogenic
radionuclides are also found in waters as a result of past fallout contaminations resulting from
the explosion in the atmosphere of nuclear devices and accidents such as those that occurred in
Chernobyl and Fukushima.
Radionuclide activity concentration in water bodies can vary according to local geological
characteristics, and climatic conditions and can be locally and temporally enhanced by releases from
[1]
nuclear installation during planned, existing and emergency exposure situations . Drinking-water
may thus contain radionuclides at activity concentrations which could present a risk to human health.
The radionuclides present in liquid effluents are usually controlled before being discharged into
[2]
the environment and water bodies. Drinking water is monitored for its radioactivity content as
[3]
recommended by the World Health Organization (WHO) so that proper actions can be taken to ensure
that there is no adverse health effects to the public. Following these international recommendations,
national regulation usually specify radionuclide authorized concentration limits for liquid effluent
discharged to the environment and radionuclide guidance levels for water bodies and drinking waters
for planned, existing and emergency exposure situations. Compliance with these limits can be assessed
using measurement results with their associated uncertainties as specified by ISO/IEC Guide 98-3 and
[4]
ISO 5667-20 .
Depending on the exposure situation, there are different limits and guidance levels that would result
in an action to reduce health risk. As an example, during a planned or existing situation, the WHO
238 234 -1
guidance level in drinking water for U and U is 10 and 1 Bq · l , respectively. The provisional
-1
guideline value for the concentration of uranium in drinking water is 30 μg · l based on its chemical
toxicity, which is predominant compared with its radiological toxicity.
NOTE 1 The guidance level is the activity concentration with an intake of 2 l/d of drinking water for one year
that results in an effective dose of 0,1 mSv/a for members of the public. This is an effective dose that represents a
[3]
very low level of risk and which is not expected to give rise to any detectable adverse health effects .
[5]
In the event of a nuclear emergency, the WHO Codex Guideline Levels mentioned that the activity
concentration might be greater.
NOTE 2 The Codex guidelines levels (GLs) apply to radionuclides contained in foods destined for human
consumption and traded internationally, which have been contaminated following a nuclear or radiological
emergency. These GLs apply to food after reconstitution or as prepared for consumption, i.e., not to dried or
concentrated foods, and are based on an intervention exemption level of 1 mSv in a year for members of the
[5]
public (infant and adult) .
Thus, the test method can be adapted so that the characteristic limits, decision threshold, detection
limit and uncertainties ensure that the radionuclide activity concentrations test results can be verified
to be below the guidance levels required by a national authority for either planned/existing situations
[6][7]
or for an emergency situation .
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ISO 13166:2020(E)

Usually, the test methods can be adjusted to measure the activity concentration of the radionuclide(s)
in either wastewaters before storage or in liquid effluents before being discharged to the environment.
The test results will enable the plant/installation operator to verify that, before their discharge,
wastewaters/liquid effluent radioactive activity concentrations do not exceed authorized limits.
The test method(s) described in this document may be used during planned, existing and emergency
exposure situations as well as for wastewaters and liquid effluents with specific modifications that
could increase the overall uncertainty, detection limit, and threshold.
The test method(s) may be used for water samples after proper sampling, sample handling, and test
sample preparation (see the relevant part of the ISO 5667 series).
This document has been developed to answer the need of test laboratories carrying out these
measurements that are sometimes required by national authorities, as they may have to obtain a
specific accreditation for radionuclide measurement in drinking water samples.
This document is one of a family of International Standards on test methods dealing with the
measurement of the activity concentration of radionuclides in water samples.
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INTERNATIONAL STANDARD ISO 13166:2020(E)
Water quality — Uranium isotopes — Test method using
alpha-spectrometry
WARNING — Persons using this document should be familiar with normal laboratory practices.
This document does not purport to address all of the safety problems, if any, associated with its
use. It is the responsibility of the user to establish appropriate safety and health practices and to
determine the applicability of any other restrictions.
IMPORTANT — It is absolutely essential that tests conducted according to this document be
carried out by suitably trained staff.
1 Scope
This document specifies the conditions for the determination of uranium isotope activity concentration
232
in samples of environmental water (including sea waters) using alpha-spectrometry and U as a
yield tracer.
A chemical separation is required to separate and purify uranium from a test portion of the sample.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 5667-1, Water quality — Sampling — Part 1: Guidance on the design of sampling programmes and
sampling techniques
ISO 5667-3, Water quality — Sampling — Part 3: Preservation and handling of water samples
ISO 11929-1, Determination of the characteristic limits (decision threshold, detection limit and limits of
the coverage interval) for measurements of ionizing radiation — Fundamentals and application — Part 1:
Elementary applications
ISO 11929-3, Determination of the characteristic limits (decision threshold, detection limit and limits of
the coverage interval) for measurements of ionizing radiation — Fundamentals and application — Part 3:
Applications to unfolding methods
ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
me a s ur ement (GUM: 1995)
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
3 Terms, definitions and symbols
For the purposes of this document, the terms, definitions, and symbols given in ISO 80000-10,
ISO 11929-1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
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ISO 13166:2020(E)

— ISO Online browsing platform: available at http:// www .iso .org/ obp
Table 1 — Symbols and definitions
Symbol Definition
232
A activity of U tracer added, in becquerel, at the date of measurement
238 235 234
c activity concentration of U or U or U, in becquerels per litre
A
*
decision threshold, in becquerels per litre
c
A
# detection limit, in becquerels per litre
c
A

lower and upper limits of the probabilistically symmetric coverage interval, in becquerels per litre
cc,
AA
< >
c , c lower and upper limits of the shortest coverage interval, in becquerels per litre
A A
R total measurement yield
r , r background count rate per second for the uranium analytes and tracer in the respective regions
0 0T
of interest (ROI) of the blank sample spectrum
R chemical yield
c
r , r gross count rate per second for the uranium analytes and tracer in the respective regions of
g gT
interest (ROI) of the test sample spectrum
t background counting time, in seconds
0
t sample counting time, in seconds
g
U expanded uncertainty, calculated by U = ku(c ) with k = 1, 2 …, in becquerels per litre
A
u(c ) standard uncertainty associated with the measurement result; in becquerels per litre
A
V volume of test sample, in litres
ε counting efficiency
4 Principle
232
The test sample is mixed with an aliquot of U tracer, followed by equilibration of the sample prior
to analysis. Chemical isolation of uranium is achieved by a concentration step (e.g. a precipitation)
followed by a specific separation step (e.g. using ion exchange chromatography).
−1
The detection limit for measurement of a test portion of about 500 ml is approximately 5 mBq · l with
a counting time of about 200 000 s.
230 226 228
Natural radionuclides such as Th, Ra and Th can be present in water and can interfere with the
counting of uranium isotopes if no chemical separation is carried out to remove these radionuclides from
the test portion. Plutonium isotopes can also interfere, if present with detectable activities in the sample.
The measured thin source is prepared by electrodeposition or coprecipitation and measured by alpha-
spectrometry using a grid chamber or a semiconductor-type apparatus. Measurements rely on the
interaction of alpha-particles with the detecting medium. This interaction creates a charge, which is
amplified and output as a voltage pulse proportional to the deposited energy of the incoming alpha-
particle.
The electric pulse from the detector is analysed by the electronic systems. Data analysis software
provides a spectrum, in which the number of pulses (counts) recorded in each energy interval is shown.
The analysis of the count rates in the uranium isotopes alpha-energy windows allows the determination
238 235 234
of the test sample activity concentration for U, U and U, after correcting for the blank count rate,
volume of the test sample and the total measurement yield (chemical yield and detection efficiency).
The chemical yield and detection efficiency are not necessarily determined separately, but are
232
determined together by measuring the total measurement yield from the net count rate of U, added
as a chemical yield tracer.
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ISO 13166:2020(E)

In order to quantify any potential interference coming from the reagents, a blank sample is prepared in
the same way as the test sample. This blank sample is prepared using a laboratory water.
For quality control, in order to quantify potential impurities in the tracer solution, another blank sample
shall be prepared with addition of tracer.
The radioactive characteristics of the main uranium isotopes are given in Table 2 (References [8], [9]).
Table 2 — Radioactive characteristics of the main uranium isotopes
Uranium Half-life Main emission energy Intensity
isotope years keV %
5 263,48 30,6
232 70,6 (±1,1)
5 320,24 69,1
4 783,5 13,2
3
233 159,1 (±0,2) × 10
4 824,2 84,3
4 722,4 28,42
5
234 2,455 (±0,006) × 10
4 774,6 71,37
4 366,1 18,8
6
235 704 (±1) × 10 4 397,8 57,19
4 414,9 3.01
4 445 26,1
6
236 23,43 (±0,06) × 10
4 494 73,8
4 151 22,33
9
238 4,468(±0,005) × 10
4 198 77,54
With a spectral resolution (FWHM full-width half-maximum height) of around 20 keV in best cases,
233 234 235 236
alpha-spectrometry cannot easily resolve U and U, nor U and U, due to the similarity in
233 236
their respective emission energies. However, U and U are normally not present in environmental
samples or in quantities above their detection limits using alpha spectrometry (see Annex D).
5 Chemical reagents and equipment
5.1 General
The chemical reagents and equipment used for chemical treatment and preparation of the source are
described in Annexes A to C, which give various alternatives. Where there are options, at least one of
the options presented shall be used.
Use only reagents of recognized analytical grade.
5.2 Chemical reagents
5.2.1 Laboratory water, used as a blank, as free as possible of chemical or radioactive impurities
(e.g. uranium isotopes), conforming to ISO 3696, grade 3.
Fresh rainwater is an example of water with a very low uranium activity concentration. The uranium
activity concentration of this water can be evaluated at the same time as interferences from reagents or
using another type of precise measurement, e.g. thermal ionization or inductively coupled plasma mass
spectrometry.
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ISO 13166:2020(E)

232
5.2.2 U tracer solution, used to determine the total yield. It can also be used to calculate the chemical
yield. The solution is prepared by the dilution of a suitable standard that provides traceability to national
and international standards. The tracer solution shall be homogeneous and stable.
The tracer solution concentration should be calculated to allow adding a small amount of this solution
in order to be in the range of activity contained in the test portion. For example, the tracer solution
−1 −1
concentration could be between 0,05 Bq · g and 1 Bq · g .
It is recommended that the activity and the purity of the tracer solution dilution be checked before
use and at regular intervals after preparation. This can be done, for example, by liquid scintillation
counting, but account needs to be taken of progeny radionuclide ingrowth. Performing a blank analysis
with tracer is a potential way to identify any presence of uranium isotope analytes in the tracer.
228 232
Th is present in the U tracer solution as a member of its decay series and has very close energy to
232
that of U. Therefore, separation between Th and U is required (References [10], [11]) to minimize the
228 232
interference of Th so that the counting yield of U is not overestimated (see Clause 4).
5.3 Equipment
Usual laboratory apparatus and in particular the following:
5.3.1 Alpha-spectrometer, of the grid chamber (with higher detection yield, but lower resolution)
or semiconductor type (with lower detection yield, but higher resolution). Operation at constant
temperature is recommended. Follow the manufacturer's instructions.
For semiconductor-type apparatus, the measurements using alpha-spectrometry depend on the
interaction of alpha-particles with ion-implanted silicon. This interaction instantly changes the
conductivity of the silicon, proportional to the energy of the incoming alpha-particle. To achieve well-
resolved spectra, the detection system needs to be maintained at a pressure <1 Pa. Resolution can be
further enhanced through increasing distance between source and detector.
232
5.3.2 Pipette, suitable for the accurate transfer of (for example 100 µl) U tracer solution with a total
precision within ±1 %.
5.3.3 Balance, for example, capable of achieving ±0,1 mg precision.
6 Sampling and samples
6.1 Sampling
Conditions of sampling shall conform to ISO 5667-1.
Filter the sample to remove solids and then acidify to < pH 2 with nitric acid or hydrochloric acid as soon
as possible after sampling prior to analysis, as specified in ISO 5667-3. Acidification prior to filtration
can result in leaching of uranium from solids component of sample.
It is important that the laboratory receive a representative sample, unmodified during transport or
storage and in an undamaged container.
6.2 Sample storage
If required, the sample is shall be stored according to ISO 5667-3.
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ISO 13166:2020(E)

7 Separation and measurement
7.1 Chemical steps
Suggested separation and source preparation strategies are outlined in Annexes A, B, and C respectively.
7.2 Measurement
7.2.1 Quality control
Equipment quality control sources shall be measured to verify that the measurement equipment is
performing within agreed limits.
239/240 230 239 244 241
A thin source of Pu (other alpha-emitters such as Th, Pu, Cm, and Am are also
possible) may be employed to check the energy calibration and the energy resolution (alpha-emissions
are in the 5,10 MeV to 5,20 MeV energy region), and there is no appreciable decay over the working life
of the source.
7.2.2 Chemical yield
The chemical yield can be considered as a quality control parameter. In general, the chemical yield
obtained is around 90 %. For very low chemical yields, it is recommended to redo the sample analysis.
The chemical yield R of the process can be calculated using Formula (1):
c
R
R = (1)
c
ε
Total yield R is the product of the chemical yield and the counting efficiency ε.
Total yield, R, is calculated from the sample spectrum using Formula (2):
rr−
()
gT 0T
R= (2)
A
7.2.3 Background
The background rate of each detector is determined with an empty source support with the lowest
activity possible present on, this shall take at least as much time as the counting of a sample.
The optimum time for the measurement of the background source can be shown to be equal to that of
the source from very low activity sources.
The blank sample analysis (i.e. analysis carried out with laboratory water containing no detectable
uranium isotope without adding tracer) value shall be compared to the totality of the background
values obtained from the same detector.
This value can be comparable to the background value measured with an empty source support in the
energy regions of uranium isotopes and of the tracer if there is no reagent or laboratory equipment
contamination.
r is the blank value or can be the background value of the detector if similar.
0
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ISO 13166:2020(E)

8 Expression of results
8.1 Spectrum analysis
...

NORME ISO
INTERNATIONALE 13166
Deuxième édition
2020-08
Qualité de l'eau — Isotopes de
l'uranium — Méthode d'essai par
spectrométrie alpha
Water quality — Uranium isotopes — Test method using alpha-
spectrometry
Numéro de référence
ISO 13166:2020(F)
©
ISO 2020

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ISO 13166:2020(F)

DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2020
Tous droits réservés. Sauf prescription différente ou nécessité dans le contexte de sa mise en œuvre, aucune partie de cette
publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique,
y compris la photocopie, ou la diffusion sur l’internet ou sur un intranet, sans autorisation écrite préalable. Une autorisation peut
être demandée à l’ISO à l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
ISO copyright office
Case postale 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Genève
Tél.: [phone]
E-mail: [e-mail]
Web: www.iso.org
Publié en Suisse
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ISO 13166:2020(F)

Sommaire Page
Avant‑propos .iv
Introduction .v
1 Domaine d’application . 1
2 Références normatives . 1
3 Termes, définitions et symboles . 1
4 Principe . 2
5 Réactifs chimiques et matériel . 3
5.1 Généralités . 3
5.2 Réactifs chimiques . 4
5.3 Matériel . 4
6 Échantillonnage et échantillons . 4
6.1 Échantillonnage . 4
6.2 Conservation des échantillons . . 5
7 Séparation et mesurage . 5
7.1 Étapes chimiques . 5
7.2 Mesurage . 5
7.2.1 Contrôle de la qualité . 5
7.2.2 Rendement chimique . 5
7.2.3 Bruit de fond . 5
8 Expression des résultats. 6
8.1 Analyse du spectre . 6
8.2 Calcul de l’activité volumique. 6
8.3 Incertitude-type . 6
8.4 Seuil de décision . 7
8.5 Limite de détection . 7
8.6 Limites des intervalles élargis . 8
8.6.1 Limites de l’intervalle élargi probabilistiquement symétrique . 8
8.6.2 Intervalle élargi le plus court . 8
9 Rapport d’essai . 9
Annexe A (informative) Séparation chimique de l’uranium .10
Annexe B (informative) Préparation de la source par électrodéposition .14
Annexe C (informative) Préparation de la source par co‑précipitation .17
Annexe D (informative) Occurrence des isotopes de l’uranium .19
Bibliographie .20
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ISO 13166:2020(F)

Avant‑propos
L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes
nationaux de normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est
en général confiée aux comités techniques de l'ISO. Chaque comité membre intéressé par une étude
a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,
gouvernementales et non gouvernementales, en liaison avec l'ISO participent également aux travaux.
L'ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui
concerne la normalisation électrotechnique.
Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont
décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier, de prendre note des différents
critères d'approbation requis pour les différents types de documents ISO. Le présent document a été
rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www
.iso .org/ directives).
L'attention est attirée sur le fait que certains des éléments du présent document peuvent faire l'objet de
droits de propriété intellectuelle ou de droits analogues. L'ISO ne saurait être tenue pour responsable
de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant
les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de
l'élaboration du document sont indiqués dans l'Introduction et/ou dans la liste des déclarations de
brevets reçues par l'ISO (voir www .iso .org/ brevets).
Les appellations commerciales éventuellement mentionnées dans le présent document sont données
pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un
engagement.
Pour une explication de la nature volontaire des normes, la signification des termes et expressions
spécifiques de l'ISO liés à l'évaluation de la conformité, ou pour toute information au sujet de l'adhésion
de l'ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles
techniques au commerce (OTC), voir www .iso .org/ avant -propos.
Le présent document a été élaboré par le comité technique ISO/TC 147, Qualité de l'eau, sous-comité
SC 3, Mesurages de la radioactivité.
Cette deuxième édition annule et remplace la première édition (ISO 13166:2014), dont elle constitue
une révision mineure. Les modifications apportées par rapport à l’édition précédente sont les suivantes:
— mise à jour de l’introduction commune;
— mise à jour du texte suite à la publication de la série de normes ISO 11929 publiées en 2019.
Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent
document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes
se trouve à l’adresse www .iso .org/ fr/ members .html.
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ISO 13166:2020(F)

Introduction
La radioactivité provenant de sources d’origine naturelle et anthropique est présente partout dans
l’environnement. Par conséquent, les masses d’eau (par exemple eaux de surface, eaux souterraines, eau
de mer) peuvent contenir des radionucléides d’origine naturelle et/ou engendrés par l’homme:
40 3 14
— les radionucléides naturels, y compris K, H et C, et ceux provenant des chaînes de désintégration
226 228 234 238 210
du thorium et de l’uranium, notamment Ra, Ra, U, U et Pb, peuvent se trouver dans l’eau
pour des raisons naturelles (par exemple, désorption par le sol et lessivage par les eaux pluviales) ou
peuvent être libérés par des processus technologiques impliquant des matériaux radioactifs existant
à l’état naturel (par exemple, extraction minière et traitement de sables minéraux ou production et
utilisation d’engrais phosphatés);
— les radionucléides artificiels, tels que les éléments transuraniens (américium, plutonium, neptunium,
3 14 90
curium), H, C, Sr et des radionucléides émetteurs gamma peuvent aussi se trouver dans les eaux
naturelles. De faibles quantités de ces radionucléides sont rejetées dans l’environnement dans le
cadre de rejets réguliers autorisés par les installations en lien avec le cycle du combustible nucléaire.
Certains de ces radionucléides, utilisés dans le cadre d’applications médicales et industrielles, sont
également libérés dans l’environnement après usage. Les radionucléides anthropiques peuvent
également se trouver dans l’eau du fait de la pollution par retombées d’éléments radioactifs rejetés
dans l’atmosphère lors de l’explosion de dispositifs nucléaires ou lors d’accidents nucléaires tels que
Tchernobyl et Fukushima.
L’activité volumique d’un radionucléide dans les masses d’eau peut varier selon les caractéristiques
géologiques et les conditions climatiques locales, et peut augmenter temporairement au niveau
local suite aux rejets d’installations nucléaires lors de situations d’exposition prévues, existantes
[1]
ou d’urgence . L’eau potable peut donc contenir des radionucléides dont l’activité volumique est
susceptible de présenter un risque pour la santé humaine.
Les radionucléides présents dans les effluents liquides sont généralement contrôlés avant leur rejet
[2]
dans l’environnement et les masses d’eau. La teneur en radioactivité de l’eau potable est surveillée
[3]
conformément aux recommandations de l’Organisation mondiale de la Santé (OMS) afin de pouvoir
prendre les mesures nécessaires pour garantir l’absence d’effets indésirables sur la santé publique.
Suite à ces recommandations internationales, la réglementation nationale précise habituellement
les concentrations limites de radionucléides autorisées pour les effluents liquides rejetés dans
l’environnement ainsi que les limites indicatives de radionucléides pour les masses d’eau et les eaux de
boisson lors de situations d’exposition prévues, existantes ou d’urgence. Le respect de ces limites peut
être vérifié à l’aide de résultats de mesurage et des incertitudes associées obtenus conformément au
[4]
Guide ISO/IEC 98-3 et à l’ISO 5667-20 .
En fonction de la situation à l’origine de l’exposition, il existe plusieurs limites et niveaux recommandés
susceptibles de déclencher une action visant à réduire le risque sanitaire. Par exemple, lors d’une
238 234
situation prévue ou existante, la limite indicative concernant l’activité volumique de U et U dans
-1
l’eau potable, conformément aux recommandations de l’OMS, est respectivement de 10 et 1 Bq· l . La
-1
limite indicative provisoire concernant la concentration en uranium dans l’eau potable est de 30 μg · l ,
en se basant sur sa toxicité chimique, qui est prédominante par rapport à sa toxicité radiologique.
NOTE 1 La limite indicative correspond à l’activité volumique avec incorporation de 2 l/j d’eau potable pendant
1 an, aboutissant à une dose efficace de 0,1 mSv/an pour les personnes du public. Cette dose efficace présente un
[3]
niveau de risque très faible qui ne devrait pas entraîner d’effets indésirables détectables sur la santé .
[5]
Les limites indicatives du codex de l’OMS mentionnent que l’activité volumique peut être supérieure
en cas de situation d’urgence d’origine nucléaire.
NOTE 2 Les limites indicatives énoncées dans le codex s’appliquent aux radionucléides contenus dans les
aliments destinés à la consommation humaine et commercialisés à l’échelle internationale qui ont été contaminés
suite à une situation d’urgence de type nucléaire ou radiologique. Ces limites indicatives s’appliquent aux
aliments après reconstitution ou tels que préparés pour la consommation; autrement dit, elles ne s’appliquent
pas aux aliments séchés ou concentrés et elles sont basées sur un niveau d’exemption d’intervention de 1 mSv/an
[5]
pour les membres du public (enfants et adultes) .
© ISO 2020 – Tous droits réservés v

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ISO 13166:2020(F)

Ainsi, la méthode d’essai peut être adaptée de telle sorte que les limites caractéristiques, le seuil de
décision, la limite de détection et les incertitudes garantissent qu’il soit possible de vérifier que les
résultats des essais portant sur l’activité volumique des radionucléides sont inférieurs aux limites
indicatives requises par une autorité nationale pour les situations planifiées/existantes ou pour une
[6][7]
situation d’urgence .
Généralement, les méthodes d’essai peuvent être ajustées pour mesurer l’activité volumique du ou
des radionucléides dans les eaux usées avant stockage, ou dans les effluents liquides avant rejet dans
l’environnement. Les résultats d’essai permettent à l’exploitant de l’installation industrielle de vérifier,
avant rejet, que les activités volumiques des radionucléides présents dans les eaux usées/dans l’effluent
liquide ne dépassent pas les limites autorisées.
La ou les méthodes d’essai décrites dans le présent document peuvent être utilisées lors de situations
d’exposition prévues, existantes ou d’urgence, ainsi que pour les eaux usées et effluents liquides, avec
des modifications spécifiques susceptibles d’augmenter l’incertitude, la limite de détection et le seuil
globaux.
La ou les méthodes d’essai peuvent être utilisées pour les échantillons d’eau après prélèvement
et manipulation appropriés des échantillons et préparation de la prise d’essai (voir la partie
correspondante de la série de l’ISO 5667).
Le présent document a été élaboré pour répondre au besoin des laboratoires d’essai réalisant ces
mesurages et qui sont parfois tenus d’obtenir une accréditation spécifique de la part d’autorités
nationales pour la réalisation de mesurages portant sur les radionucléides dans les échantillons d’eau
potable.
Le présent document fait partie d’une série de Normes internationales portant sur des méthodes d’essai
visant à mesurer de l’activité volumique des radionucléides dans des échantillons d’eau.
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NORME INTERNATIONALE ISO 13166:2020(F)
Qualité de l'eau — Isotopes de l'uranium — Méthode
d'essai par spectrométrie alpha
AVERTISSEMENT — Il convient que les utilisateurs du présent document connaissent les
pratiques courantes de laboratoire. Le présent document n’a pas la prétention d’aborder tous
les éventuels problèmes de sécurité liés à son utilisation. Il incombe à l’utilisateur d’établir des
pratiques appropriées en matière de santé et de sécurité et de déterminer l’applicabilité de toute
autre restriction éventuelle.
IMPORTANT — Il est absolument essentiel que les essais réalisés conformément au présent
document soient effectués par du personnel qualifié.
1 Domaine d’application
Le présent document spécifie les conditions relatives à la détermination de l’activité volumique des
isotopes de l’uranium dans des échantillons d’eau environnementale (y compris les eaux de mer) par
232
spectrométrie alpha en utilisant U comme traceur.
Une séparation chimique est requise pour séparer et purifier l’uranium de la prise d’essai.
2 Références normatives
Les documents suivants sont cités dans le texte de sorte qu’ils constituent, pour tout ou partie de leur
contenu, des exigences du présent document. Pour les références datées, seule l’édition citée s’applique.
Pour les références non datées, la dernière édition du document de référence s’applique (y compris les
éventuels amendements).
ISO 3696, Eau pour laboratoire à usage analytique — Spécification et méthodes d'essai
ISO 5667-1, Qualité de l’eau — Échantillonnage — Partie 1: Lignes directrices pour la conception des
programmes et des techniques d’échantillonnage
ISO 5667-3, Qualité de l'eau — Échantillonnage — Partie 3: Conservation et manipulation des
échantillons d'eau
ISO 11929-1, Détermination des limites caractéristiques (seuil de décision, limite de détection et
extrémités de l'intervalle élargi) pour mesurages de rayonnements ionisants — Principes fondamentaux et
applications — Partie 1: Applications élémentaires
ISO 11929-3, Détermination des limites caractéristiques (seuil de décision, limite de détection et
extrémités de l'intervalle élargi) pour mesurages de rayonnements ionisants — Principes fondamentaux et
applications — Partie 3: Applications aux méthodes de déconvolution
ISO 80000-10, Grandeurs et unités — Partie 10: Physique atomique et nucléaire
Guide ISO/IEC 98-3, Incertitude de mesure — Partie 3: Guide pour l’expression de l’incertitude de mesure
(GUM: 1995)
ISO/IEC 17025, Exigences générales concernant la compétence des laboratoires d'étalonnages et d'essais
3 Termes, définitions et symboles
Pour les besoins du présent document, les termes, définitions et symboles donnés dans l’ISO 80000-10,
l’ISO 11929-1 ainsi que les suivants s’appliquent.
© ISO 2020 – Tous droits réservés 1

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ISO 13166:2020(F)

L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en
normalisation, consultables aux adresses suivantes:
— IEC Electropedia: disponible à l’adresse http:// www .electropedia .org/ ;
— ISO Online browsing platform: disponible à l’adresse https:// www .iso .org/ obp.
Tableau 1 — Symboles et définitions
Symbole Définition
232
A activité du traceur U ajouté, en becquerels, à la date du mesurage
238 235 234
c activité volumique de U, U ou U, en becquerels par litre
A
*
seuil de décision, en becquerels par litre
c
A
#
limite de détection, en becquerels par litre
c
A

limites basse et haute de l’intervalle élargi probabilistiquement symétrique, en becquerels par litre
cc,
AA
< >
c , c limites basse et haute de l’intervalle élargi le plus court, en becquerels par litre
A A
R rendement total du mesurage
r , r taux de comptage du bruit de fond par seconde dans les régions d’intérêt respectives (ROI) des
0 0T
analytes de l’uranium et du traceur du spectre de l’échantillon à blanc
R rendement chimique
c
r , r taux de comptage brut par seconde dans les régions d’intérêt respectives (ROI) des analytes de
g gT
l’uranium et du traceur du spectre de la prise d’essai
t durée de comptage du bruit de fond, en secondes
0
t durée de comptage de la prise d’essai, en secondes
g
U incertitude élargie, calculée par U = ku(c ) avec k = 1, 2 …, en becquerels par litre
A
u(c ) incertitude-type associée au résultat de mesure, en becquerels par litre
A
V volume de la prise d’essai, en litres
ε rendement de comptage
4 Principe
232
La prise d’essai est mélangée à une aliquote de traceur U, puis mise à l’équilibre avant l’analyse.
La purification chimique de l’uranium est obtenue par une étape de concentration (par exemple une
précipitation) suivie d’une étape de séparation spécifique (par exemple par chromatographie d’échange
d’ions).
−1
Pour le mesurage d’une prise d’essai d’environ 500 ml, la limite de détection est d’environ 5 mBq · l
pour une durée de comptage de l’ordre de 200 000 s.
230 226 228
Les radionucléides naturels tels que Th, Ra et Th peuvent être présents dans l’eau et interférer
avec le comptage des isotopes de l’uranium si aucune séparation chimique n’a été effectuée pour
éliminer ces radionucléides de la prise d’essai. Les isotopes du plutonium peuvent également interférer,
s’ils sont présents à des niveaux d’activité détectables dans l’échantillon.
La source mince mesurée est préparée par électrodéposition ou co-précipitation et mesurée par
spectrométrie alpha à l’aide d’un appareillage de type chambre à grille ou semi-conducteur. Les
mesurages reposent sur l’interaction des particules alpha avec le milieu de détection. Cette interaction
génère une charge qui est amplifiée et transmise sous forme d’une impulsion de tension proportionnelle
à l’énergie déposée de la particule alpha entrante.
L’impulsion électrique provenant du détecteur est analysée par des systèmes électroniques. Le logiciel
d’analyse de données produit un spectre montrant le nombre d’impulsions (coups) enregistrées dans
chaque intervalle d’énergie.
2 © ISO 2020 – Tous droits réservés

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ISO 13166:2020(F)

L’analyse des taux de comptage dans les fenêtres d’énergie alpha des isotopes de l’uranium permet de
238 235 234
déterminer l’activité volumique de la prise d’essai pour U, U et U, après prise en compte des
corrections liées au taux de comptage de l’essai à blanc, au volume de la prise d’essai et au rendement
total du mesurage (rendement chimique et rendement de détection).
Le rendement chimique et le rendement de détection ne sont pas nécessairement déterminés
séparément, mais sont déterminés ensemble en mesurant le rendement total du mesurage à partir du
232
taux de comptage net de U, ajouté comme traceur.
Pour quantifier toute interférence potentielle due aux réactifs, un échantillon à blanc est préparé
de la même manière que la prise d’essai. Cet échantillon à blanc est préparé en utilisant une eau de
laboratoire.
Aux fins du contrôle de la qualité, pour quantifier les impuretés potentielles dans la solution de traceur,
un autre échantillon à blanc doit être préparé en ajoutant le traceur.
Les caractéristiques radioactives des principaux isotopes de l’uranium sont données dans le Tableau 2
(Références [8], [9]).
Tableau 2 — Caractéristiques radioactives des principaux isotopes de l’uranium
Isotope de Période Énergie d’émission principale Intensité
l’uranium
années keV %
5 263,48 30,6
232 70,6 (±1,1)
5 320,24 69,1
4 783,5 13,2
3
233 159,1 (±0,2) × 10
4 824,2 84,3
4 722,4 28,42
5
234 2 455 (±0 006) × 10
4 774,6 71,37
4 366,1 18,8
6
235 704 (±1) × 10 4 397,8 57,19
4 414,9 3,01
4 445 26,1
6
236 23,43 (±0,06) × 10
4 494 73,8
4 151 22,33
9
238 4,468 (±0,005) × 10
4 198 77,54
Avec une résolution spectrale (FWHM, largeur totale à mi-hauteur du maximum) d’environ 20 keV
233
dans les cas les plus favorables, la spectrométrie alpha peut difficilement faire la distinction entre U
234 235 236
et U, ou U et U, en raison de la similitude de leurs énergies d’émission respectives. Toutefois,
233 236
U et U ne sont généralement pas présents dans les échantillons prélevés dans l’environnement
ou, s’ils le sont, pas en quantités supérieures à leurs limites de détection par spectrométrie alpha (voir
Annexe D).
5 Réactifs chimiques et matériel
5.1 Généralités
Les réactifs chimiques et le matériel utilisés pour le traitement chimique et la préparation de la source
sont décrits dans les Annexes A à C, qui proposent diverses alternatives. Lorsqu’il existe plusieurs
possibilités, au moins l’une d’entre elles doit être utilisée.
Utiliser uniquement des réactifs de qualité analytique reconnue.
© ISO 2020 – Tous droits réservés 3

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ISO 13166:2020(F)

5.2 Réactifs chimiques
5.2.1 Eau de laboratoire, utilisée comme blanc, aussi exempte que possible d’impuretés chimiques ou
radioactives (telles que des isotopes de l’uranium) et conforme à l’ISO 3696, qualité 3.
L’eau de pluie, recueillie récemment, est un exemple d’eau présentant une très faible activité volumique
d’uranium. L’activité volumique de l’uranium de cette eau peut être évaluée en même temps que les
interférences dues aux réactifs ou en utilisant un autre type de mesurage de précision, par exemple
l’ionisation thermique ou la spectrométrie de masse avec plasma couplé par induction.
232
5.2.2 Solution de traceur U, utilisée pour déterminer le rendement total. Elle peut également être
utilisée pour calculer le rendement chimique. La solution est préparée par dilution d’un étalon approprié
pouvant être relié à des étalons nationaux et internationaux. La solution de traceur doit être homogène
et stable.
Il convient de calculer la concentration de la solution de traceur de manière à pouvoir ajouter une faible
quantité de cette solution pour atteindre la plage d’activité de la prise d’essai. Par exemple, l’activité
−1 −1
massique de la solution de traceur pourrait être comprise entre 0,05 Bq · g et 1 Bq · g .
Il est recommandé de vérifier l’activité et la pureté de la dilution de solution de traceur avant usage
et à intervalles réguliers après sa préparation. Cette vérification peut être effectuée, par exemple,
par comptage par scintillation liquide, mais il est nécessaire de tenir compte de la re-croissance des
descendants du radionucléide. Réaliser une analyse à blanc avec le traceur est l’une des méthodes
possibles pour détecter la présence d’analytes isotopes de l’uranium dans le traceur.
228 232
Th est présent dans la solution de traceur U, car c’est un élément de sa chaîne de désintégration,
232
et a une énergie très proche de celle de U. Par conséquent, une séparation de Th et U est requise
228
(Références [10], [11]) pour réduire au minimum l’interférence de Th afin de ne pas surestimer le
232
rendement de comptage de U (voir Article 4).
5.3 Matériel
Matériel courant de laboratoire et en particulier les éléments suivants:
5.3.1 Spectromètre alpha, de type chambre à grille (avec un rendement de détection élevé, mais une
faible résolution) ou de type semi-conducteur (avec un faible rendement de détection, mais une haute
résolution). Un fonctionnement à température constante est recommandé. Suivre les instructions du
fabricant.
Pour un appareillage de type semi-conducteur, les mesurages par spectrométrie alpha dépendent de
l’interaction des particules alpha avec le silicium à implantation ionique. Cette interaction fait varier
instantanément la conductivité du silicium, proportionnellement à l’énergie de la particule alpha
entrante. Pour obtenir des spectres ayant une résolution satisfaisante, il est nécessaire de maintenir
le système de détection à une pression inférieure à 1 Pa. La résolution peut encore être améliorée en
augmentant la distance entre la source et le détecteur.
232
5.3.2 Pipette, adaptée au transfert exact de solution de traceur U (par exempl
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 13166
ISO/TC 147/SC 3
Water quality — Uranium isotopes —
Secretariat: AFNOR
Test method using alpha-spectrometry
Voting begins on:
2020­04­14
Qualité de l'eau — Isotopes de l'uranium — Méthode d'essai par
spectrométrie alpha
Voting terminates on:
2020­06­09
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 13166:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2020

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ISO/FDIS 13166:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
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Published in Switzerland
ii © ISO 2020 – All rights reserved

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ISO/FDIS 13166:2020(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
4 Principle . 2
5 Chemical reagents and equipment . 3
5.1 General . 3
5.2 Chemical reagents . 3
5.3 Equipment . 4
6 Sampling and samples . 4
6.1 Sampling . 4
6.2 Sample storage . 4
7 Separation and measurement . 5
7.1 Chemical steps . 5
7.2 Measurement . 5
7.2.1 Quality control . 5
7.2.2 Chemical yield . 5
7.2.3 Background. 5
8 Expression of results . 6
8.1 Spectrum analysis . 6
8.2 Calculation of activity concentration . 6
8.3 Standard uncertainty . 6
8.4 Decision threshold . 7
8.5 Detection limit . 7
8.6 Limits of the coverage interval . 8
8.6.1 Limits of the probabilistically symmetric coverage interval. 8
8.6.2 The shortest coverage interval . 8
9 Test report . 9
Annex A (informative) Chemical separation of uranium .10
Annex B (informative) Precipitation of the source by electrodeposition .13
Annex C (informative) Preparation of the source by coprecipitation .16
Annex D (informative) Occurrence of uranium isotopes .18
Bibliography .19
© ISO 2020 – All rights reserved iii

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ISO/FDIS 13166:2020(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non­governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 3,
Radiological methods.
This second edition cancels and replaces the first edition (ISO 13166:2014), of which it constitutes a
minor revision. The changes compared to the previous edition are as follows:
— Update of the common introduction.
— Update of the text considering the new ISO 11929 series published in 2019.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved

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ISO/FDIS 13166:2020(E)

Introduction
Radioactivity from several naturally occurring and anthropogenic sources is present throughout
the environment. Thus, water bodies (e.g. surface waters, ground waters, sea waters) can contain
radionuclides of natural, human­made, or both origins:
40 3 14
— Natural radionuclides, including K, H, C, and those originating from the thorium and uranium
226 228 234 238 210
decay series, in particular Ra, Ra, U, U, and Pb, can be found in water for natural reasons
(e.g. desorption from the soil and wash off by rain water) or can be released from technological
processes involving naturally occurring radioactive materials (e.g. the mining and processing of
mineral sands or phosphate fertilizer production and use);
— Human­made radionuclides, such as transuranium elements (americium, plutonium, neptunium,
3 14 90
curium), H, C, Sr, and gamma emitting radionuclides can also be found in natural waters.
Small quantities of these radionuclides are discharged from nuclear fuel cycle facilities into the
environment as the result of authorized routine releases. Some of these radionuclides used for
medical and industrial applications are also released into the environment after use. Anthropogenic
radionuclides are also found in waters as a result of past fallout contaminations resulting from
the explosion in the atmosphere of nuclear devices and accidents such as those that occurred in
Chernobyl and Fukushima.
Radionuclide activity concentration in water bodies can vary according to local geological
characteristics, and climatic conditions and can be locally and temporally enhanced by releases from
[1]
nuclear installation during planned, existing and emergency exposure situations . Drinking­water
may thus contain radionuclides at activity concentrations which could present a risk to human health.
The radionuclides present in liquid effluents are usually controlled before being discharged into
[2]
the environment and water bodies. Drinking water is monitored for its radioactivity content as
[3]
recommended by the World Health Organization (WHO) so that proper actions can be taken to ensure
that there is no adverse health effects to the public. Following these international recommendations,
national regulation usually specify radionuclide authorized concentration limits for liquid effluent
discharged to the environment and radionuclide guidance levels for water bodies and drinking waters
for planned, existing and emergency exposure situations. Compliance with these limits can be assessed
using measurement results with their associated uncertainties as specified by ISO/IEC Guide 98-3 and
[4]
ISO 5667­20 .
Depending on the exposure situation, there are different limits and guidance levels that would result
in an action to reduce health risk. As an example, during a planned or existing situation, the WHO
­1
guidance level in drinking water for uranium-238 and uranium-234 is 10 and 1 Bq · l , respectively. The
­1
provisional guideline value for the concentration of uranium in drinking water is 30 μg · l based on its
chemical toxicity, which is predominant compared with its radiological toxicity.
NOTE 1 The guidance level is the activity concentration with an intake of 2 l/d of drinking water for one year
that results in an effective dose of 0,1 mSv/a for members of the public. This is an effective dose that represents a
[3]
very low level of risk and which is not expected to give rise to any detectable adverse health effects .
[5]
In the event of a nuclear emergency, the WHO Codex Guideline Levels mentioned that the activity
concentration might be greater.
NOTE 2 The Codex guidelines levels (GLs) apply to radionuclides contained in foods destined for human
consumption and traded internationally, which have been contaminated following a nuclear or radiological
emergency. These GLs apply to food after reconstitution or as prepared for consumption, i.e., not to dried or
concentrated foods, and are based on an intervention exemption level of 1 mSv in a year for members of the
[5]
public (infant and adult) .
Thus, the test method can be adapted so that the characteristic limits, decision threshold, detection
limit and uncertainties ensure that the radionuclide activity concentrations test results can be verified
to be below the guidance levels required by a national authority for either planned/existing situations
[6][7]
or for an emergency situation .
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ISO/FDIS 13166:2020(E)

Usually, the test methods can be adjusted to measure the activity concentration of the radionuclide(s)
in either wastewaters before storage or in liquid effluents before being discharged to the environment.
The test results will enable the plant/installation operator to verify that, before their discharge,
wastewaters/liquid effluent radioactive activity concentrations do not exceed authorized limits.
The test method(s) described in this document may be used during planned, existing and emergency
exposure situations as well as for wastewaters and liquid effluents with specific modifications that
could increase the overall uncertainty, detection limit, and threshold.
The test method(s) may be used for water samples after proper sampling, sample handling, and test
sample preparation (see the relevant part of the ISO 5667 series).
This document has been developed to answer the need of test laboratories carrying out these
measurements that are sometimes required by national authorities, as they may have to obtain a
specific accreditation for radionuclide measurement in drinking water samples.
This document is one of a family of International Standards on test methods dealing with the
measurement of the activity concentration of radionuclides in water samples.
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 13166:2020(E)
Water quality — Uranium isotopes — Test method using
alpha-spectrometry
WARNING — Persons using this document should be familiar with normal laboratory practices.
This document does not purport to address all of the safety problems, if any, associated with its
use. It is the responsibility of the user to establish appropriate safety and health practices and to
determine the applicability of any other restrictions.
IMPORTANT — It is absolutely essential that tests conducted according to this document be
carried out by suitably trained staff.
1 Scope
This document specifies the conditions for the determination of uranium isotope activity concentration
in samples of environmental water (including sea waters) using alpha-spectrometry and 232U as a
yield tracer.
A chemical separation is required to separate and purify uranium from a test portion of the sample.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 5667­1, Water quality — Sampling — Part 1: Guidance on the design of sampling programmes and
sampling techniques
ISO 5667­3, Water quality — Sampling — Part 3: Preservation and handling of water samples
ISO 11929­1, Determination of the characteristic limits (decision threshold, detection limit and limits of
the coverage interval) for measurements of ionizing radiation — Fundamentals and application — Part 1:
Elementary applications
ISO 11929­3, Determination of the characteristic limits (decision threshold, detection limit and limits of
the coverage interval) for measurements of ionizing radiation — Fundamentals and application — Part 3:
Applications to unfolding methods
ISO 80000­10, Quantities and units — Part 10: Atomic and nuclear physics
ISO/IEC Guide 98­3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
me a s ur ement (GUM: 1995)
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
3 Terms, definitions and symbols
For the purposes of this document, the terms, definitions, and symbols given in ISO 80000-10,
ISO 11929-1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
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ISO/FDIS 13166:2020(E)

— ISO Online browsing platform: available at http:// www .iso .org/ obp
Table 1 — Symbols and definitions
Symbol Definition
232
A activity of U tracer added, in becquerel, at the date of measurement
238 235 234
c activity concentration of U or U or U, in becquerel per litre
A
*
decision threshold, in becquerel per litre
c
A
# detection limit, in becquerel per litre
c
A

lower and upper limits of the probabilistically symmetric coverage interval, in becquerel per litre
cc,
AA
< >
c , c lower and upper limits of the shortest coverage interval, in becquerel per litre
A A
R total measurement yield
r , r background count rate per second for the uranium analytes and tracer in the respective regions
0 0T
of interest (ROI) of the blank sample spectrum
R chemical yield
c
r , r gross count rate per second for the uranium analytes and tracer in the respective regions of
g gT
interest (ROI) of the test sample spectrum
t background counting time, in seconds
0
t sample counting time, in seconds
g
U expanded uncertainty, calculated by U = ku(c ) with k = 1, 2 …, in becquerel per litre
A
u(c ) standard uncertainty associated with the measurement result; in becquerel per litre
A
V volume of test sample, in litres
ε counting efficiency
4 Principle
232
The test sample is mixed with an aliquot of U tracer, followed by equilibration of the sample prior
to analysis. Chemical isolation of uranium is achieved by a concentration step (e.g. a precipitation)
followed by a specific separation step (e.g. using ion exchange chromatography).
−1
The detection limit for measurement of a test portion of about 500 ml is approximately 5 mBq · l with
a counting time of about 200 000 s.
230 226 228
Natural radionuclides such as Th, Ra and Th can be present in water and can interfere with the
counting of uranium isotopes if no chemical separation is carried out to remove these radionuclides from
the test portion. Plutonium isotopes can also interfere, if present with detectable activities in the sample.
The measured thin source is prepared by electrodeposition or coprecipitation and measured by alpha-
spectrometry using a grid chamber or a semiconductor-type apparatus. Measurements rely on the
interaction of alpha­particles with the detecting medium. This interaction creates a charge, which is
amplified and output as a voltage pulse proportional to the deposited energy of the incoming alpha-
particle.
The electric pulse from the detector is analysed by the electronic systems. Data analysis software
provides a spectrum, in which the number of pulses (counts) recorded in each energy interval is shown.
The analysis of the count rates in the uranium isotopes alpha-energy windows allows the determination
238 235 234
of the test sample activity concentration for U, U and U, after correcting for the blank count rate,
volume of the test sample and the total measurement yield (chemical yield and detection efficiency).
The chemical yield and detection efficiency are not necessarily determined separately, but are
232
determined together by measuring the total measurement yield from the net count rate of U, added
as a chemical yield tracer.
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ISO/FDIS 13166:2020(E)

In order to quantify any potential interference coming from the reagents, a blank sample is prepared in
the same way as the test sample. This blank sample is prepared using a laboratory water.
For quality control, in order to quantify potential impurities in the tracer solution, another blank sample
shall be prepared with addition of tracer.
The radioactive characteristics of the main uranium isotopes are given in Table 2 (References [8], [9]).
Table 2 — Radioactive characteristics of the main uranium isotopes
Uranium Half-life Main emission energy Intensity
isotope years keV %
5 263,48 30,6
232 70,6 (±1,1)
5 320,24 69,1
4 783,5 13,2
3
233 159,1 (±0,2) × 10
4 824,2 84,3
4 722,4 28,42
5
234 2,455 (±0,006) × 10
4 774,6 71,37
4 366,1 18,8
6
235 704 (±1) × 10 4 397,8 57,19
4 414,9 3.01
4 445 26,1
6
236 23,43 (±0,06) × 10
4 494 73,8
4 151 22,33
9
238 4,468(±0,005) × 10
4 198 77,54
With a spectral resolution (FWHM full-width half-maximum height) of around 20 keV in best cases,
233 234 235 236
alpha-spectrometry cannot easily resolve U and U, nor U and U, due to the similarity in
233 236
their respective emission energies. However, U and U are normally not present in environmental
samples or in quantities above their detection limits using alpha spectrometry (see Annex D).
5 Chemical reagents and equipment
5.1 General
The chemical reagents and equipment used for chemical treatment and preparation of the source are
described in Annexes A to C, which give various alternatives. Where there are options, at least one of
the options presented shall be used.
Use only reagents of recognized analytical grade.
5.2 Chemical reagents
5.2.1 Laboratory water, used as a blank, as free as possible of chemical or radioactive impurities
(e.g. uranium isotopes), conforming to ISO 3696, grade 3.
Fresh rainwater is an example of water with a very low uranium activity concentration. The uranium
activity concentration of this water can be evaluated at the same time as interferences from reagents or
using another type of precise measurement, e.g. thermal ionization or inductively coupled plasma mass
spectrometry.
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ISO/FDIS 13166:2020(E)

232
5.2.2 U tracer solution, used to determine the total yield. It can also be used to calculate the chemical
yield. The solution is prepared by the dilution of a suitable standard that provides traceability to national
and international standards. The tracer solution shall be homogeneous and stable.
The tracer solution concentration should be calculated to allow adding a small amount of this solution
in order to be in the range of activity contained in the test portion. For example, the tracer solution
−1 −1
concentration could be between 0,05 Bq · g and 1 Bq · g .
It is recommended that the activity and the purity of the tracer solution dilution be checked before
use and at regular intervals after preparation. This can be done, for example, by liquid scintillation
counting, but account needs to be taken of progeny radionuclide ingrowth. Performing a blank analysis
with tracer is a potential way to identify any presence of uranium isotope analytes in the tracer.
228 232
Th is present in the U tracer solution as a member of its decay series and has very close energy to
232
that of U. Therefore, separation between Th and U is required (References [10], [11]) to minimize the
228 232
interference of Th so that the counting yield of U is not overestimated (see Clause 4).
5.3 Equipment
Usual laboratory apparatus and in particular the following:
5.3.1 Alpha-spectrometer, of the grid chamber (with higher detection yield, but lower resolution)
or semiconductor type (with lower detection yield, but higher resolution). Operation at constant
temperature is recommended. Follow the manufacturer's instructions.
For semiconductor-type apparatus, the measurements using alpha-spectrometry depend on the
interaction of alpha-particles with ion-implanted silicon. This interaction instantly changes the
conductivity of the silicon, proportional to the energy of the incoming alpha-particle. To achieve well-
resolved spectra, the detection system needs to be maintained at a pressure <1 Pa. Resolution can be
further enhanced through increasing distance between source and detector.
232
5.3.2 Pipette, suitable for the accurate transfer of (for example 100 µl) U tracer solution with a total
precision within ±1 %.
5.3.3 Balance, for example, capable of achieving ±0,1 mg precision.
6 Sampling and samples
6.1 Sampling
Conditions of sampling shall conform to ISO 5667­1.
Filter the sample to remove solids and then acidify to < pH 2 with nitric acid or hydrochloric acid as soon
as possible after sampling prior to analysis, as specified in ISO 5667-3. Acidification prior to filtration
can result in leaching of uranium from solids component of sample.
It is important that the laboratory receive a representative sample, unmodified during transport or
storage and in an undamaged container.
6.2 Sample storage
If required, the sample is shall be stored according to ISO 5667-3.
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ISO/FDIS 13166:2020(E)

7 Separation and measurement
7.1 Chemical steps
Suggested separation and source preparation strategies are outlined in Annexes A, B, and C respectively.
7.2 Measurement
7.2.1 Quality control
Equipment quality control sources shall be measured to verify that the measurement equipment is
performing within agreed limits.
239/240 230 239 244 241
A thin source of Pu (other alpha­emitters such as Th, Pu, Cm, and Am are also
possible) may be employed to check the energy calibration and the energy resolution (alpha-emissions
are in the 5,10 MeV to 5,20 MeV energy region), and there is no appreciable decay over the working life
of the source.
7.2.2 Chemical yield
The chemical yield can be considered as a quality control parameter. In general, the chemical yield
obtained is around 90 %. For very low chemical yields, it is recommended to redo the sample analysis.
The chemical yield R of the process can be calculated using Formula (1):
c
R
R = (1)
c
ε
Total yield R is the product of the chemical yield and the counting efficiency ε.
Total yield, R, is calculated from the sample spectrum using Formula (2):
rr−
()
gT 0T
R= (2)
A
7.2.3 Background
The background rate of each detector is determined with an empty source support with the lowest
activity possible present on, this shall take at least as much time as the counting of a sample.
The optimum time for the measurement of the background source can be shown to be equal to that of
the source from very low activity sources.
The blank sample
...